Field-induced dissociation
1. fluorescent materials
Abstract
A method is developed for deducing the electron affinity of disordered organic semiconductors from spectroscopic thin-film studies of the ionization energy and the optical gap energy, combined with field-induced dissociation (FID) device experiments that are analyzed with kinetic Monte Carlo simulations using a methodology that has been presented by de Jong et al., Phys. Rev. B 112, 224202 (2025). The FID experiments are carried out for a set of eight organic semiconductor materials that are often used in organic light-emitting diodes. The analysis is focused on the š¯›¼ and š¯›½ isomers of the blue fluorescent emitter material 2-methyl-9,10-di-naphthyl-anthracene. For these two materials, the experimental ionization energy, the optical gap energy, the exciton binding energy, and the electron affinity are shown to be consistent with the results of quantum-chemical calculations, presented by G. TirimbĆ² et al., Phys. Rev. B 112, 224203 (2025). For all fluorescent emitter materials studied, the FID experiments reveal an exciton binding energy of approximately 1.0ā€“1.2 eV, whereas for a thermally activated delayed fluorescence material, a slightly smaller value is obtained.
This work has been published in Physical Review B
"Electron affinity and binding energy of excitons in disordered organic semiconductors. III. Multimethod study for films of the blue fluorescent emitter MADN"
(Phys. Rev. B 112, 224204 (2025).)
Supplemental material
2. phosphorescent materials
Abstract
In phosphorescent organic light-emitting diodes (OLEDs), which are commonly used in display applications, metal-organic emitter molecules are usually blended at a small concentration in a host material. Their efficiency and operational lifetime depend strongly on the energies of the highest occupied molecular orbital EHOMO, the lowest unoccupied molecular orbital ELUMO, and the triplet exciton binding energy ET,b of the emitter materials. However, determining ELUMO and ET,b remains a challenge. In this work, a methodology is demonstrated for determining ET,b of iridium-based phosphorescent emitters from field-induced dissociation experiments, and for using this energy to determine ELUMO. The consistency of the analysis method, which makes use of kinetic Monte Carlo simulations, is demonstrated by a variation of the host materials and the blend composition, and by providing a comparison with quantum-chemical calculations. The binding energy of triplet excitons in Ir-based phosphorescent emitters is found to lie typically in the range of 1.0ā€“1.3 eV.
This work has been accepted in Advanced Functional Materials
"Exciton binding energy of phosphorescent emitter molecules in organic light-emitting diodes"
(Adv. Funct. Mater. in press (2026).)
Main paper